Transportation of containers in container filling machines is a critical issue, for production rates have reached several tens of thousands of units per hour. During most of handling operations (e.g. filling, capping, transfer), containers are generally mounted on gripping elements provided at the periphery of a conveying starwheel.
In order to comply with the production rates, rotational speed of such a conveying starwheel (having e.g. a diameter of about 3 m and a capacity of around 50 containers) is higher than 15 rpm. Therefore, strong centrifugal forces are exerted on the containers, which imply a risk of the containers being ejected from the gripping elements, or at least a risk of the containers tilting and adopting a wrong position with respect of the normal vertical position. The risk of ejection or wrong positioning is higher for filled containers, given their weight. Ejection of a filled container may result in machine damage or even human injury. In addition to liquid waste, wrong position of a filled container may result in machine malfunction and/or damage during container transfer or capping.
The container industry is familiar with devices provided for ensuring that articles are normally held during the handling operations. When the articles are preforms or empty containers, any wrong positioned article is usually ejected by means of a safety device, see e.g. European patent application No. EP 1 781 460. However such a safety device is not adapted to filled containers, which should not be ejected when positioned in a wrong way, for the reasons stated hereabove.